Internal combustion engine



JML 31, i939 l A. ECKE-MLLER M INTERNAL COMBUSTION ENGINE Filed April 2,`1936 2 sheets-Sheet 1 Jan. 4.31, 1939. A. Bom-:MULLER INTERNALQOMBUSTION ENGINE www Filed April 2, 1936 Sheets-Shei 2 #gill Jn @fentor maaier lan. 31, 193e @MEAN UNITED STATES @PATENT @FWCE INTERNALCOIWBUSTION ENGINE Alfred Bokemiiller, Gaggenau, Baden, Germany,assignor to Daimler-Benz Aktiengesellschaft, Stuttgart-Unterturkheim,Germany Application April 2, 1936, Serial No. 72,255 Y In Germany April4, 1935 20 Claims. (Cl. 12B- 65) My invention relates to internalcombustion interval between the opening of the outlet and engines of thetwo-cycle type and has for its obthe dead center instant in suchmachines equals ject to improve the scavenging operation and to theinterval between the dead center instant and obtain an increasedeiiciency. the closing of the outlet, any reduction of the 5 Moreparticularly, my invention relates to tWofirst interval will equallyreduce the second intercycle engines in which the inlet and the outletval and will thus adversely affect the emciency oi ports are provided inthe cylinder walls and are the scavenging operation. On the other hand,controlled by the piston and by a tubular sleeve any increase of theseintervals reduces the eiecsurrounding the same. tive stroke and involvesa loss of fresh charge.

1o I attain the objects of my invention by con- A higher effectivepressure has been attained l0 trolling the relative motion of the pistonand with two-cycle engines in which one or more the control sleeve insuch a manner that the valves are used to control the scavengingoperatimed relationship of the instants at which the tion, thescavenging air rinsing the 'cylinder from inlet and outlet ports areopened and closed by one end thereof to the other.

lo the piston and the sleeve is non-symmetrical rel- By thenon-symmetrical controlas above eX- liti ative to the instant of thepassage of the piston plained I secure an ellcent scavenging operationthrough its lower dead center point, the interval and a high averageeffective pressure by simple between the opening of the outlet and thedead means, a single control sleeve only being procenter instant beinglarger than the interval vided and the inlet and outlet ports being lo-2o between the dead center instant and the closing cated in the cylinderwalls close to the lower dead 20 of the outlet and/or the intervalbetween the center point which is of particular advantage for opening ofthe inlet and the dead center instant the control of the inlet andoutlet ports in high being shorter than that between the dead centerspeed engines. instant and the closing of the inlet. Preferably, Theprovision of a plurality of groups of inlet Q5 the control of the inletand outlet ports is so ports has the further advantage that the control25 timed that the outlet is opened before the inlet is thereof may bedifferently timed in a simple manopened and that the outlet is closedshortly bener and that a plurality of scavenging currents iore crsubstantially together with the inlet. of different directions ordifferent pressures may A highly enicient scavenging operation will bebe produced in a suitable succession, whereby attained by the provisionof two groups of inseparate currents of air or gas may be used for 30let ports which are controlled in a differently scavenging the cylinderand for charging it.

timed manner, one group of inlet ports being Further objects of myinvention will appear controlled by the piston only, whereby the timedfrom the description following hereinafter and relationship of theinstants of opening and closthe features of novelty will loe-pointed outin 3 3 ing is symmetrical relative to the instant of the the claims. 35lower dead center position of the piston, and the A preferred embodimentof my invention is other group of inlet ports being controlled by theillustrated in the drawings. combined function of the piston and thecontrol Fig. 1 shows a partial axial section through a sleeve so as tobe left open after the iirst group cylinder of the machine illustratinga part of L1 n has been closed. the crank shaft and the means foroperating the 40 My invention is equally applicable to machines pistonand the control sleeve, the section being of the Diesel type in which aliquid fuel is intaken along line l-I of Fig. 2;

jected into the cylinder which is charged with Fig. 2 is a section takenalong line 2-2 of air or to engines of the type in which a gaseous Fig.l and .17, or vaporized fuel is compressed in the cylinder. Figs. 3 to 8are diagrams illustrating the rela- 45 Experience has shown that theaverage effective positions of the cylinder, the control sleeve tivepressure attainable in two-cycle engines is and the piston in successiveinstants. limited, when the inlet and outlet ports provided Fig. 9 showsa partial axial section through in the cylinder walls are solelycontrolled by the the cylinder illustrating a second form of the 5opiston with a timed relationship of the instants inlet port. 50 of theopening and closing which is symmetrical Fig. 10 shows a partial axialsection through with regard to the lower dead center instant. thecylinder illustrating the main inlet port ol This applies particularlyto automotive engines the engine. y which are designed to produce ashigh a torque In Fig. 1, the cylinder g provided with the 55 as possibleover a large range of speeds. As the customary cooling jacket illsupports on its gg upper end a cylinder head or cover Il which has acylindrical downward projection I2. This projection is slightly spacedfrom the inner wall oi' the cylinder g so as to define an annular gap I3therewith. A fuel-injecting mechanism I4 which may or may not include apre-combustion chamber is inserted in the cylinder II in centralposition to inject liquid fuel into the highly heated air compressed inthe cylinder. The air is fed into the cylinder from a source ofcompressed air, such as a scavenging pump (not shown) through two groupsof inlet ports e and e', when the piston k approaches its lower deadcenter position.

Substantially at the same time the outlet ports a are opened. It will benoted from Fig. 2 that the inlet ports e and e traverse the coolingjacket I0 and the cylinder y and have the general directions indicatedby the arrows in Fig. 2. These arrows converge towards a point m whichis eccentrically located in the cylinder remote from the outlet ports a.Preferably the inlet ports e and e' are substantially radially directedto the axis of the cylinder, as sliown in Fig. 1, or these ports may beslightly upwardly directed at an acute angle with the axis of thecylinder g, as shown in Figs. 9 and 10. Moreover, it will be noted thatthe main inlet ports e are located at a slightly lower level than theauxiliary inlet ports e' and that the outlet ports a are substantiallyradially directed and diametrically opposed to the ports e. Some of theports are controlled by the combined function of the piston k and of asleeve valve or slide s which is guided within the cylinder. The upperend of the slide projects into the annular gap I3 and its lower end isprovided with two diametrically opposed trunnions I5. Intermediate itsends the slide s is provided with two groups of openings es and as, theopenings e's cooperating with the inlet ports e .and the openings aswith the outlet ports a. Moreover, the slide is provided with twolongitudinal slots 1' extending from its lower end upwardlyapproximately to the level of the upper walls of the openings e's. Itwill be obvious, however, that the slots r need not extend all the wayto the bottom of the sleeve s but may be cut off near the bottom to formrectangular openings. These slots r straddle the mouths h of the ports ewhich project inwardly from the cylinder y for direct cooperation withthe piston k. As will be seen from Fig. 10, the mouths h are of such aform that piston k in its lower dead center position will stillbe incontact therewith.

If desired, these projecting mouths h may be made separate from thecylinder g and suitably inserted therein for easy manufacture althoughthey are shown integral with the cylinder in the drawings. The sectionof the crank shaft which is allotted to the cylinder shown in Fig. 1 isprovided with three crank pins. The central crank pin 20 is connectedwith the piston k by the customary connecting rod 2| while the two othercrank pins are connected with the trunnions I5 by auxiliary connectingrods 22. Preferably, the crank pin 20 is displaced from 130 to 180degrees in advance of the two lateral crank pins to secure the propertiming of the control slide s relative to the piston k.

The slots r must be so dimensioned with reference to the stroke impartedto the reciprocatory sleeve s by the cranks and the connecting rods 22that the mouths h will not interfere with the upper walls of the slotsr. If desired, rectangular openings may be substituted for the slots r,as

previously described. The piston k is guided by the sleeve s.

The openings as and es cooperate with the upper end of the piston incontrolling the outlet ports a and the auxiliary inlet ports e', thecontrol sleeve s moving substantially in a direction opposite to that ofthe piston. The opposite motion of the piston and the control slide orsleeve has the advantage that the ports are fully opened and fullyclosed at a higher speed.

The main inlet ports e, however, are controlled solely by the pistonindependently of the motion of the control slide or sleeve s.

The operation will be explained hereinafter with reference to thediagrams shown in Figs. 3 to 8 which illustrate successive instantsduring one revolution of the crank shaft. In Fig. 3 the elements assumethe position in which the opening of the outlet ports a commences. Thecrank pin 20 operating the piston is in the position A1 and the crankpins operating the control sleeve in the position B1.

It will be noted that the point A1 is ahead of the point B1 by the angleB. This angle may be chosen from to 180 degrees. 'I'he piston movesdownwardly and the control sleeve upwardly. Therefore, the outlet portsa will be very quickly uncovered by the upper edge of the piston and bythe opening as of the control sleeve. The main inlet ports e are stillcovered by the piston and the auxiliary inlet ports e' by the controlsleeve.

Fig. 4 illustrates the instant at which the main inlet ports e areuncovered by the upper edge of the piston, the main crank having arrivedat E1.

Fig. 5 shows the instant at which the opening of the auxiliary inletports e' by the sleeve opening es commences, the main crank arriving atE1 shortly after having passed the lower dead center position UT. Atthis time, the sleeve s is-rapidly moving downwardly, whereby theauxiliary inlet ports e' will be uncovered within a short interval whilethe outlet ports a are being closed. The main inlet e is fully opened.

The closing of the outlet ports is effected by the opposite motion ofthe downwardly moving sleeve and of the upwardly moving piston. The endof the closing operation is illustrated in Fig. 6. In this instant, thecrank has arrived at the point A2. The main inlet ports e are partlycovered again by the piston, whereas the auxiliary inlet ports are beinguncovered by the opening e's.

Shortly afterwards, the elements arrive at the position shown in Fig. 'lin which the crank passes through the point Ez. At this instant, themain inlet ports e have just been completely covered by the piston k,Whereas the auxiliary inlet ports e' are just fully opened.

In Fig. 8 the crank arrives at the point Ez. At this instant, theauxiliary inlet ports e' are fully closed. As the upward motion of thepiston and the downward motion of the sleeve are comparatively rapid,the auxiliary inlet ports e were closed at a high speed. 'I'his has theadvantage, that the full cross-section of the auxiliary inlet ports e'is kept open until shortly before the closing begins, namely until theinstant of Fig. 7, whereby a very effective scavenging or charging orsupercharging operation is rendered possible without delaying theclosing of the auxiliary inlet to such an extent that the scavenging orcharging medium entering therethrough would meet with a considerablecounteracting compression pressure.

In Fig. 6 the entire control diagram is shown with reference to thecrank circle. It will be noted that the interval between the instants Aiand UT is larger than the interval between the instants UT and A2 whichmeans that the outlct ports are opened sooner with reference to thelower dead center point than they are closed. Inversely, the intervalbetween E1 and UT is shorter than the interval between UT and theinstant E'z at which all of the inlet ports are completely closed.Therefore, the outlet diagram A1-A2=a and the inlet diagram Ei--Eioverlap in a favorable manner, as is shown in Fig. 6.

The inlet diagram is obtained by the control diagram El-Ezze of the maininlet ports situated symmetrically relative to the lower dead centerpoint of the piston and by the control diagram E'1-E'2=e' of theauxiliary inlet ports situated very non-symmetrically relative to thedead center point.

The main inlet ports may serve to scavenge the cylinder, whereas theauxiliary or additional inlet ports are used in the main for chargingand supercharging the cylinder. The charging medium may be any suitablefluid such, for example, as air, when the invention is applied to Dieselengines, or a gas or a fuel mixture when the invention is applied tomachines provided with a carburetor. In the two latter cases the gas orfuel mixture may be fed to the cylinder through the auxiliary inletports, whereas pure scavenging air is fed to the main inlet ports.Moreover, the pressure at which the air charge enters through the mainor auxiliary inlet ports may be made different by suitably choosing anddimensioning the sources supplying the scavenging medium.

In the embodiment illustrated in the drawings, provision is made for asupercharging of the cylinder through the auxiliary inlet ports.However, the control points A1, A2, E1, Ez, E'1, Ez may be so arrangedrelative to each other that Ez coincides with A2 or that A2 is precededby E2 and E'2 without departing from the above described principalrelation of the inlet or outlet intervals.

In view of the low position of the control openings, the sleeve may beso designed that it terminates substantially in the level of theopenings as and e's and does not engage the gap I3.

Further modifications will readily appear to anyone skilled in the art.

What I claim is:

1. In a two-cycle internal combustion engine, comprising in combination,a cylinder, a slide valve in said cylinder, a piston in said slidevalve, an inlet and outlet port for said cylinder controlled by saidpiston and slide valve, a further inlet port for said cylindercontrolled by said piston alone, and means drivably connecting saidpiston with said slide valve, the angular relationship of saidconnecting means being such that the inlet and outlet port controlled bythe piston and slide valve will be controlled asymmetrically and theinlet port controlled by the piston alone will be controlledsymmetrically with respect to the lower dead center point of the piston.

2. The combination according to claim 1 including means for introducinga stream of charging fluid into saidcylinder through said rst inlet portand means for introducing a stream of scavenging uid into said cylinderthrough said second inlet port.

3. In a two-cycle internal combustion engine, the combination comprisinga cylinder provided with two groups of inlet ports and one group ofoutlet ports, a tubular sleeve having cooperating openings guided forreciprocatory movement in said cylinder, a piston guided forreciprocatory movement in said sleeve and cooperating with the openingsin said sleeve for controlling one group of said inlet portssymmetrically with respect to the lower dead center point of saidpiston, and means interconnecting said piston and sleeve for controllingthe other group of inlet ports asymmetrically with respect to said lowerdead center point, and in such a manner that said second group of inletports remain open after said first group of said inlet ports has beenclosed, and means for supplying said rst group of inlet ports with ascavenging fluid, and means for supplying said second group of inletports with a charging uid.

4. The combination according to claim 3 in which the ports oi" eachgroup are circumferentially distributed and in which the second group ofinlet ports are adjacent the outlet ports.

5. The combination according to claim 3 in which the ports in each groupare circumferentially distributed, andl in which the second group ofinlet ports' are adjacent the outlet ports, al1 of said inlet portsconverging toward a point eccentricaly located within the cylinder atthe side remote from said outlet ports.

6. In a two-cycle internal combustion engine, the combination comprisinga cylinder provided with inlet and outlet ports, a tubular sleeve havingcooperating openings and guided for recip rocatory movement in saidcylinder, a piston guided for reciprocatory movement in said sleeve, acrank shaft having a plurality of crank pins and a plurality ofconnecting rods one of which joins one of said crank pins to said pistonand the other o-f which joins the other crank pins to said sleeve, saidpiston operating crank pin leading said sleeve operating crank pins byapproximately 130 to 180, whereby said `inlet and outlet ports arecontrolled asymmetrically with respect to the lower dead center point ofsaid piston, the outlet ports being opened sooner with respect .to saiddeadcenter point than they are closed and the inlet ports being openedlater with respect to said dead center point than they are closed.

7. In a two-cycle internal combustion engine. the combination comprisinga cylinder provided with two groups of inlet ports and with outletports, a tubular sleeve having cooperating openings for controlling onegroup of inlet ports and said outlet ports and guided for reciprocatorymovement in said cylinder, a piston guided for reciprocatory movement insaid sleeve and controlling a second group of said inlet ports and meansinterconnecting said sleeve and piston in such a manner that the firstgroup of inlet ports and outlet ports are controlled in anasymmetrically timed relationship relative to the passage of the pistonthrough its lower dead center point.

8. In an internal combustion engine, the combination of a cylinderhaving two groups of inlet ports and one group of outletk ports, theinlet ports of one of said groups having internally projecting mouths, atubular sleeve having elongated openings circumferentially closelyfitting said projecting mouths, guided for reciprocatory motion in saidcylinder and adapted to control dii said second group of inlet ports,and a. piston guided for reciprocatory motion in said sleeve and adaptedto open and close said mouths.

9. A two-cycle internal combustion engine comprising in combination, acylinder, a slide valve in said cylinder, a piston in said slide valve,an inlet and outlet port for said cylinder controlled by said piston andslide valve, and a further inlet port for said cylinder controlled bysaid piston alone.

10. A two-cycle internal combustion engine comprising in combination, acylinder, a slide valve in said cylinder, a piston in said slide valve,an inlet and outlet port for said cylinder controlled by said piston andslide valve, a further inlet port for said cylinder controlled by saidpiston alone, and means drivably connecting said piston and side valvefor opening the rst named inlet port shortly after the outlet port hasbeen opened and closing it shortly after the outlet port has beenclosed, and for opening the second inlet port shortly before the outletport has been closed and closing it after the outlet port and the firstnamed inlet port have been closed.

11. The combination according to claim 9 in which the inlet portscontrolled by the piston and slide valve are arranged opposite to theoutlet ports and are adapted to charge the cylinder, and the secondnamed inlet ports controlled by the piston alone are adjacent to saidoutlet ports and are adapted to scavenge the cylinder.

12. The combination according to claim 9 in which the inlet portscontrolled by the piston and slide valve are arranged opposite to theoutlet port and are adapted to charge the cylinder and the second namedinlet ports controlled by the piston alone are arranged adjacent to saidoutlet port and are adapted to scavenge the cylinder, the outlet portbeing substantially radially directed to the. axis of the cylinder andthe inlet ports being slightly upwardly directed and converge toward apoint eccentrically located within the cylinder at the side remote fromsaid outlet ports.

13. A two-cycle internal combustion engine comprising in combination, acylinder, an outlet port for said cylinder directed radially to the axisof said cylinder, an inlet port for said cylinder slightly upwardlydirected at an angle to the axis of the cylinder and arrangedk oppositeto the outlet port, a further inlet port slightly upwardly directed tothe axis of the cylinder and located adjacent the outlet port at aslightly lower level than said rst inlet port, both of said inlet portsconverging towards a point eccentrically located within the cylinder atthe side remote from said outlet port, a mouth on said further inletport projecting inwardly from said cylinder, a tubular slide valve insaid cylinder having opposite ports respectively controlling theopposite inlet and outlet ports and having a longitudinal slotstraddling the mouth of said further inlet port, a v

piston in said tubular slide valve controlling the ports in said slidevalve and the further inlet port in said cylinder and means drivablyconnecting the piston with the slide valve, the angular relationship ofsuch connecting means being such that the inlet and outlet portscontrolled by the piston and slide valve will be controlledasymmetrically and the inlet port controlled by the piston alone will becontrolled symmetrically with respect to the lower dead center point ofthe pis- 14. A two-cycle internal combustion engine comprising incombination, a cylinder, an outlet port for said cylinder directedradially to the axis of the cylinder, an inlet port for said cylinderslightly upwardly directed at an angle to the, axis of the cylinder andarranged opposite said outlet port, a further inlet port slightlyupwardly directed to the axis of the cylinder and located adjacent saidoutlet port at a slightly lower level than said first inlet port, bothof said inlet ports converging toward a point eccentrically locatedwithin said cylinder at the side remote from said outlet port, a mouthon said further inlet port projecting inwardly from said cylinder, atubular slide valve in said cylinder having opposite ports respectivelycontrolling the opposite inlet and outlet ports and having alongitudinal slot straddling the mouth of said further inlet port, apiston in said tubular slide valve controlling the ports in said slidevalve and the further inlet port in said cylinder, means drivablyconnecting the piston with said slide valve, the angular relationship ofthis connecting means being such that the inlet port controlled by saidslide valve will be opened shortly after the outlet port has been openedand will be closed shortly after the outlet port has been closed, andthe inlet port controlled by the piston alone will be open shortlybefore the outlet port has been closed and will be closed shortly afterthe outlet port and said first main inlet port have been closed, wherebythe inlet and outlet ports controlled by said piston and slide valvewill be controlled asymmetrically and the inlet port controlled by thepiston alone will be controlled symmetrically with respect to the lowerdead center point of the piston. 15. A two-cycle internal combustionengine as set forth in claim 13 in combination with means forintroducing a stream of charging iiuid into said cylinder through saidfirst inlet port, and means for introducing scavenging fluid into saidcylinder through said further inlet port.

16. The method of controlling a two-cycle internal combustion enginehaving two groups of inlet ports and one. group of outlet ports,including the steps of opening the outlet ports, opening one group ofinlet ports a short time thereafter, closing the outlet ports, closingsaid first group of inlet ports a short time after said outlet portshave been closed, opening the second group of inlet ports a short timebefore the outlet ports have been closed and closing said second groupof inlet ports shortly before said outlet ports and said rst group ofinlet ports have been closed.

17. The method of controlling a two-cycle internal combustion enginehaving two groups of inlet ports and one group of outlet ports,including the steps of controlling one group of inlet ports and saidoutlet ports asymmetrically with respect to the lower dead center pointof the cylinder piston, and controlling the other group of inlet portssymmetrically withl respect to the lower dead center point of thecylinder piston.

18. The method according to claim 17 including the steps of introducinga stream of chargf with inlet and outlet ports, a tubular sleeveg havingcooperating openings and guided for reciprocatory movement in saidcylinder, a piston guided for reciprocatory movement in said sleeve, andmeans interconnecting said sleeve and piston in such a manner that saidinlet and outlet ports are asymmetrically controlled, the outlet portsbeing opened before the inlet ports with respect to the lower deadcenter point of the piston and both said inlet and outlet ports beingclosed at substantially the same time.

20. In a two-cycle internal combustion engine, the combinationcomprising a cylinder provided with groups of inlet and outlet ports,said outlet ports being radially directed in one side of said cylinderand said groups of inlet ports being axially displaced on the oppositeside of said cylinder and directed at an oblique angie to the radius andaxis of said cylinder, a tubular sleeve having cooperating openings andguided for reciprocatory movement in said cylinder, a piston guided forreciprocatory movement in said sleeve, and means interconnecting saidsleeve and piston in such a manner that said inlet and outlet ports areasymmetrically controlled, the outlet ports being opened sooner withrespect to the lower ldead center point of the piston than they areclosed, and said inlet ports being opened later with respect to saiddead center point than they 10

